/**
  * Starts dynamic caches.
  *
  * @throws IgniteCheckedException If failed.
  */
 private void startCaches() throws IgniteCheckedException {
   cctx.cache()
       .prepareCachesStart(
           F.view(
               reqs,
               new IgnitePredicate<DynamicCacheChangeRequest>() {
                 @Override
                 public boolean apply(DynamicCacheChangeRequest req) {
                   return req.start();
                 }
               }),
           exchId.topologyVersion());
 }
  /** {@inheritDoc} */
  @SuppressWarnings({"MismatchedQueryAndUpdateOfCollection"})
  @Nullable
  @Override
  public GridDhtPartitionMap update(
      @Nullable GridDhtPartitionExchangeId exchId, GridDhtPartitionMap parts) {
    if (log.isDebugEnabled())
      log.debug(
          "Updating single partition map [exchId=" + exchId + ", parts=" + mapString(parts) + ']');

    if (!cctx.discovery().alive(parts.nodeId())) {
      if (log.isDebugEnabled())
        log.debug(
            "Received partition update for non-existing node (will ignore) [exchId="
                + exchId
                + ", parts="
                + parts
                + ']');

      return null;
    }

    lock.writeLock().lock();

    try {
      if (stopping) return null;

      if (lastExchangeId != null && exchId != null && lastExchangeId.compareTo(exchId) > 0) {
        if (log.isDebugEnabled())
          log.debug(
              "Stale exchange id for single partition map update (will ignore) [lastExchId="
                  + lastExchangeId
                  + ", exchId="
                  + exchId
                  + ']');

        return null;
      }

      if (exchId != null) lastExchangeId = exchId;

      if (node2part == null)
        // Create invalid partition map.
        node2part = new GridDhtPartitionFullMap();

      GridDhtPartitionMap cur = node2part.get(parts.nodeId());

      if (cur != null && cur.updateSequence() >= parts.updateSequence()) {
        if (log.isDebugEnabled())
          log.debug(
              "Stale update sequence for single partition map update (will ignore) [exchId="
                  + exchId
                  + ", curSeq="
                  + cur.updateSequence()
                  + ", newSeq="
                  + parts.updateSequence()
                  + ']');

        return null;
      }

      long updateSeq = this.updateSeq.incrementAndGet();

      node2part = new GridDhtPartitionFullMap(node2part, updateSeq);

      boolean changed = false;

      if (cur == null || !cur.equals(parts)) changed = true;

      node2part.put(parts.nodeId(), parts);

      part2node = new HashMap<>(part2node);

      // Add new mappings.
      for (Integer p : parts.keySet()) {
        Set<UUID> ids = part2node.get(p);

        if (ids == null)
          // Initialize HashSet to size 3 in anticipation that there won't be
          // more than 3 nodes per partition.
          part2node.put(p, ids = U.newHashSet(3));

        changed |= ids.add(parts.nodeId());
      }

      // Remove obsolete mappings.
      if (cur != null) {
        for (Integer p : F.view(cur.keySet(), F0.notIn(parts.keySet()))) {
          Set<UUID> ids = part2node.get(p);

          if (ids != null) changed |= ids.remove(parts.nodeId());
        }
      }

      changed |= checkEvictions(updateSeq);

      consistencyCheck();

      if (log.isDebugEnabled()) log.debug("Partition map after single update: " + fullMapString());

      return changed ? localPartitionMap() : null;
    } finally {
      lock.writeLock().unlock();
    }
  }